It **could** be possible to alter the save button on draw tool to actually take a screenshot using the built-in functionality.
I did it in Komic.
As draw tool is a WAF, it could be possible.
I currently don't know if draw tool has JS in Kindle or if it uses an external source through wifi.
I don't know it as I don't have my Kindle right now!

It's a web page accessed through the Internet, unless it stores its web pages someone other than /var/local/waf/draw. (Or cached somehow....)